Fix CFMetaData#getColumnDefinitionFromColumnName()

patch by Benedict Elliott Smith; reviewed by Aleksey Yeschenko for
CASSANDRA-7074
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	CHANGES.txt
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/cache/RefCountedMemory.java